AAS 98-157

NONLINEAR ADAPTIVE STATE ESTIMATOR APPROACH TO ATTITUDE AND ORBIT DETERMINATION USING ONLY A MAGNETOMETER

F. Curti - University of Rome "La Sapienza", Italy

Abstract

In the present paper the Nonlinear Adaptive State Estimator (NASE) technique is applied to the attitude and orbit determination of the Italian San Marco 5 satellite, which was a spinning satellite (flown in 1988) with a three-axis magnetometer along the principal inertia axes. The technique is based on an adaptive scheme for directly building the estimator gain by using the magnetometer outputs. The NASE is functioning as an optimal filter with respect to a suitable Lyapunov function, which is selected for studying the stability of the estimator. Besides the optimality characteristics, the estimator is adapting with the disturbances arising from the noise and the high order terms of the linearization process. Moreover, thanks to the adaptation behaviour of the filter, the mismatching between the actual geomagnetic field and the Earth magnetic model is also balanced. The paper contributes to optimizing the values of the NASE parameters and sets up an automatic procedure for finding them.

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